“…[3][4][5][6][7][8] However, targeted delivery of a murine-based retroviral vector to a specific subpopulation of human cells has yet to be truly achieved. Initial attempts to change viral tropism were done through the use of pseudotyped viruses; [9][10][11] MuLV is able to incorporate vesicular stomatitis virus G glycoprotein (VSV-G), influenza virus hemagglutinin (HA), or heterologous retroviral glycoproteins, although this expands viral host range rather than restrict cell tropism. Even though several groups have generated chimeric Envligand fusion proteins designed to bind on to transferrin receptor, galactose receptor or the high density lipoprotein receptor, none of these fusion proteins were successfully incorporated into infectious viral particles.…”